Fix jar to work with custom shell wrappers.

TUTORIAL.md

@@ -317,7 +317,7 @@ project's :main namespace, but specifying this option triggers AOT for
 uberjars, so if you wish to avoid this or use a different :main for
 the shell wrapper vs uberjar you can specify a :main ns inside the
 :shell-wrapper map. You may also specify a :bin key, which should
-point to a file in <tt>resources/</tt> directory to use as a shell
+point to a file relative to the project's root to use as a shell
 wrapper template instead of the default. The <tt>format</tt> function
 is called with the contents of this file along with the necessary
 classpath and the main namespace, so put %s in the right place. See

src/leiningen/core.clj

@@ -130,6 +130,7 @@
 (defn arglists [task-name]
   (:arglists (meta (resolve-task task-name))))
 
+;; TODO: some arities of some tasks require projects while others don't
 (defn project-needed? [task-name]
   (every? #{'project} (map first (arglists task-name))))
 

src/leiningen/jar.clj

@@ -30,10 +30,10 @@
             (format "bin/%s" (:name project)))))
 
 (defn- shell-wrapper-contents [project bin-name main deps-fileset]
-  (if-let [is (-> (.getContextClassLoader (Thread/currentThread))
-                  (.getResourceAsStream bin-name))]
-    (slurp* is)
-    (format bin-template
+  (let [bin-file (file bin-name)]
+    (format (if (.exists bin-file)
+              (slurp* bin-file)
+              bin-template)
             (script-classpath-for project deps-fileset) main)))
 
 (defn- shell-wrapper-filespecs [project deps-fileset]